Peel the onion and cut into half rings. Peel, wash and cut the potatoes into small cubes. Clean and wash the Brussels sprouts and cut or quarter them depending on the size. Scald the tomatoes with hot water, peel off the skin and dice the tomatoes. Finely chop the garlic and parsley.
Heat olive oil in a pot. Add onions, potatoes and garlic and fry until golden brown. Add the Brussels sprouts and rice and fill up with the vegetable stock. Let everything simmer for 20 minutes. Drain the beans, add them and simmer for another 5 minutes. Now add the tomato pieces and the parsley to the soup and season with salt and pepper.
Sprinkle the soup with freshly grated parmesan cheese before serving.